Acid-proof alloys



Patented Dec. 13, 1932 UNITED STATES PATENT OFFICE EMANUEL VALENTA, OFI'ILSEN, CZECHOSLOVAKIA, ASSIGNOR TO FIRM LIMITED COMPANY, FORMERLYSKODA WORKS, OF PILSEN, GZECHOSLOVAKIA ACID-PROOF ALLOYS N0 Drawing.Application filed October 7, 1929, Serial No. 398,099, and inCzechoslovakia October 31, 1928.

Alloys composed of iron and silicon hav-' ing a silicon content of from7 to 20% and which strongly resist the effect of acids and othercorrosive media are generally known.

These alloys are fairly strong when their silicon content lies between 7and 12%, but their resistance to, acids is smaller than that of alloyswith a higher silicon content. If the content of silicon increases above12% these alloys become chemically more resistant, but at the cost oftheir strength and alloys with more than 16% silicon'are so brittle thatthe production of comparatively simple castings becomes very difiicult.The process hitherto employed for their production consists in meltingdown a high percentage ferro-silicon with iron and in remeltingand thisis the disadvantage of this process-the resulting product in order toobtain a homogeneous material suitable for casting.

The object of the present invention is to improve both the quality andthe casting properties of the acid-proof alloys. The improvement of thementioned properties is attained by alloying titanium with the usualacid-proof alloys composed of iron and silicon. Titanium may replace thesilicon in the acid-proof alloys used in' practice either partly orcompletely. A real improvement both in the mechanical and in the castingproperties as compared with the usual acidproof alloys is establishedwith the group of alloys in which titanium partly replaces the silicon,namely, in thosealloys which contain 0.01 to 10%of titanium togetherwith 7 to 20% of silicon. Alloys obtained in this manner aredistinguished by their complete homogeneity and are free from gases andimpurities. It is to be emphasized that no remelting is necessary intheir production and that already on the first melting down a materialis obtained of uniform, fine-grained structure without oxidizing orother liquidations, and possessing an increased resistance to corrosion,an increased tenacity and of definitely decreased brittleness. Furtherthe suitability for casting of these alloys is improved by the infiuenceof the titanium. The titanium effects an increase of the number of thecrystal centres and prevents the formation of trans-crystallizationzones when the wall strengths are large and in'the transitions. Itinfluences the uniformity of the crystallized structure and diminishesthe tendency to form cracks in the castings.

The melting of the acid-proof alloys which form the sub ect of thepresent invention is carried out in the usual melting apparatus, that isin the cupola furnace or-as' is especially advantageous for thesealloysin the flame furnace and chiefly in the electric furnace.

I claim:

Acid-proof alloys consisting of from 0.01 to 10% of titanium, from 7 to20% of silicon and the balance iron.

In testimony whereof I afiix my signature.

EMANUEL VALENTA.

